Improvement in pyrogenous lubricating-o



UNITED STATES ATENT OFFICE.

SAMUEL DOYVNER AND JOSHUA MERRILL, OF BOSTON, MASSACHUSETTS.

IMPROVEMENT IN PYROGENOUS LUBRlCATlNG-OlLS.

Specification forming part of Letters Patent No. 15,418. dated July I9, 185.6.

To all whom it may concern Be it known that we, SAMUEL DOWNER and JOSHUA MERRILL, both of Boston, in the county of Suffolk and Commonwealth of Massachusetts, have discovered an Improvement in the Manufacture of Lubricating-Oils from Goals, Goal-Tar, and Bitumens; and we do hereby declare that the following is a full and exact description thereof.

The nature of the application of our discovery consists in modifying the oils obtained for lubricating purposes so as to fit them for general use under the varying conditions of high and low temperatures. These oils are of two kinds, as obtained from different materials, and have different boiling-points, being thin mobile oils or thicker oils having a higher oleaginous character. The obstacle to the extended use of some ofthese oilsis that, although by the thermometer they have high boilingpoints, yet when exposed to currents of air from moving machinery they evaporate at common temperatures. They need a fixity of character in currents of air. Now, the results of experiments continued for a long time on all natural bodies soluble in these oils have shown that some bitumens and the various kinds of caoutchouc and gutta-percha dissolved in these oils prevent the contact of currents of air and give to the oils from coal, coal-tar, and bitumens the desired amount of fixity while in use as lubricators. It is true that the most fixed dense oils having high oleaginous characters are carried off by currents of air in a less degree than those with lower boiling-points, but among those some require an addition of bitumen, caoutchouc, or guttapercha to give them permanency under friction. We find that such addition does not impair the lubricating power of the oil; but in the case of the best known of these oils their lubricating power is increased after the addition. A simple addition of bitumen or caoutchouc or gutta-percha to thelubricatingoils obtained from coals, coal-tar, or bitumens allows the pyrogenic oil to become impregnated with a small quantity of the bitumen or caoutchouc, and when the oil is applied to machinery the effect of changing the oil is produced by the heat of friction; but we pre fer to heat the oil and dissolve the bitumen or caoutchouc at once in it, adding such proportion of either bitumen or caoutchouc as the nature of the oil in air seems to require.

To enable those skilled in art to apply our discovery, we proceed to describe our process.

The purified oil, known as paraffine-oil, coup-oil, or similar oils, placed in an iron vessel containing steam-pipes, is to be heated by high-pressure steam or surcharged steam. Bitumen of the elastic kind, caoutchouc, or gutta-percha equal in quantity to from onefourth of one per cent. to two per cent. of the weight of the oil is then to be placed in pails composed of fine wiregauze and suspended in the oil, and the heat continued.

For general purposes we use East Indian, African, or Para caoutchouc. Where the cost of the oil is less and the purposes to which it is to be applied are less important we use native elastic bitumen or coarse East Indian gutta-percha. At first the caoutchouc divides in the oil and gives its usual character of expanding in it to form a kind of emulsion but after a little time, and especially when the tempera ture rises to 220 to 280 Fahrenheit, this property is lost, and. the caoutchouc becomes a constituent part of the oil, and cannot be obtained in a separate state from it. lVcjudge of the progress of this change by takinga few drops of the oil, and, after cooling, applying the thumb and finger to the oil, we separate them and observe if a thread or fiber appears. The heat must be continued until the distended fibers of the caoutchouc disappear, and when the oil has cooled it is fit for use as a lubricator.

lVe judge of the quantity of caoutchouc required by a particular kind of pyrogenic oil, either after trial of the oil on a machine called a d ynalneter, (used in factories to determine the amount of friction,) or, having dissolved two per cent. of caoutchouc in it, we dilute it with fresh oil until it has the desired resisting power or endurance on the machine.

It is well known to us that caoutchouc has been used for solidifying mixtures of grease, oils, alkalies, glue, and water whendistended by oil of turpentine. It has also been diffused through rape-oil to form a thick unctuous compound and in cheap oils to give body as a crude paint-oil. Attempts have been made to use it in an emulsive condition in oil of turpentine as an addition to lard-oil for lubricating purposes. Similar efforts have been made to dissolve caoutchouc in the common fixed 0il,whieh it chemically repels; but in all these cases the results have been negative or the mixtures formed have not served as lubricators. The books have stated generally that india-rubber dissolves in the fixed oils. This we do not find to be the case with the common oils, such as lard, whale, rape-seed, and olive oil, the rubber being merely diffused in an expanded state through them. Therefore we disclaim the use of all mixtures in which caoutchouc is diffused without its chemical state being altered, and we confine the application of our discovery to the improvement of the qualities of the lubricating-oils from coals, coal-tar, and bitumens solely. Our improvement of these 

